The present invention relates to a centring and clamping device which permits a two-dimensional geometric positioning X-Y of a sheet-metal assembly such as a bodywork element or of a mechanical part in a piloting hole provided for this purpose, and its clamping in the Z axis.
The techniques normally used separate the centring and clamping functions.
Document FR2757437 discloses in particular a centring and gripping tool of the type comprising a pilot organ borne on the end of a casing and gripping organs. This tool includes means of pivoting and translational drive of the gripping organs between a centring position in which the gripping organs are retracted inside the pilot organ and several gripping positions in which the gripping organs project outside the pilot organ and rest on the part, these drive means being arranged to simultaneously produce the pivotal and translational drive of the gripping organs.
Document FR2755049 discloses a pilot grip for centring, gripping or holding a part, comprising a pilot borne by a casing and linearly mobile between a position where it is withdrawn in the casing and a position where it projects out of the casing. Means of driving the pilot in linear displacement also drives gripping organs in linear displacement, these gripping organs being drivable in linear displacement between two extreme gripping and releasing positions by second drive means which are independent of the means driving the pilot.
Document FR2733930 discloses a device for indexing a part through a hole in this part, comprising a sleeve having an upper face forming a support for the part, a piston mounted in the sleeve to slide under the action of drive means between a withdrawn position inside the sleeve and a deployed position in which it extends projecting from the upper supporting face of the sleeve with an end-portion forming an indexation pin, and a system for locking the part on the upper supporting face of the sleeve comprising at least one jaw mounted mobile on the centring pin in order to move under the action of control means between an active position in which it forms a stop for the part and an inactive position in which it allows free passage to the indexation pin through the hole of the part.
The aim of the present invention is to propose a new centring and clamping device which more closely links the gripping and clamping functions, compared with the state of the art illustrated by the aforementioned documents, in particular with piloting holes of small diameter, for example less than 25 mm, and opening out into a hollow body.
This aim is achieved with a centring and clamping device permitting a geometric management X, Y, Z of a sheet-metal assembly or a mechanical assembly.
According to the invention, this device comprises a hollow pilot procuring a centring management X, Y, fitted with at least two retractable hooks procuring a clamping management Z and each provided with a lug, and powered by a piston which slides inside the hollow pilot. This piston is provided with a characteristic groove which permits the drive in rotation of the hooks by means of their respective lugs.
The grooved piston is advantageously driven in translation by a three-point system permitting locking in clamping position, and actuated by a pneumatic jack or a manual three-point system.
The assembly (pilot, piston, hooks) is mounted on a supporting nosepiece which determines the supporting face of the part to be clamped. A washer inserted between the fixing face of the pilot and the base of the supporting nosepiece permits the adjustment of the thickness of the part that is to be clamped by modification of its thickness.
The level of the hooks (position of the lugs relative to the axes of rotation) is set through an adjusting screw. Dynamic washers inserted between the thrust head of the three-point system and the adjusting screw permit the absorption of any variations in thickness of the part to be clamped, without damage to the axes of rotation.
The whole of the system is integrated in a housing which can be fixed by three of its faces or by the supporting nosepiece in a mechanical assembly.